Guitar amplifiers (also known as “amps”) amplify the sound produced by electric guitars, bass guitars, and acoustic guitars or other instruments. Many amplifiers are built into cabinets that also contain integrated loudspeakers. These combination units are also often referred to simply as “amplifiers” or “amps.”
Combination amplifiers are used in a number of situations. Musicians can use them for solo or group practice, and also for live performances, or gigs. Because of this, it is often desirable for guitar amplifiers to be portable; portability, however is often at odds with performance in terms of sound quality, acoustic power, battery life, and other features. Therefore, musicians often require multiple amplifiers for different situations.
Originally, all amplifiers were constructed using vacuum tubes. These “tube amps” provided a warm and rich sound that is still preferred by many musicians. Vacuum tubes are large and unwieldy, however, and tube amps are often quite heavy and not portable. While semi-conductors are able to replicate many of the functions of vacuum tubes, and some musicians prefer the purer sound of solid-state amplifiers, the tube amp “sound” is the acoustic goal that most amplifiers attempt to meet.
Amplifiers with open and closed back cabinets are known in the art. The sound produced by closed-back cabinets is more directional because the sound is not able to travel as easily out of the sides or back of the amplifier. In addition, closed-back cabinets produce a tighter bass response. In contrast, open-back cabinets are less directional because sound can issue from the front and back of the enclosure, making the sound seem to come from all around the amplifier. This can allow other musicians to hear the amplifier better.
Because of their weight, even some musicians who would prefer a tube amplifier will select a more portable, solid-state amplifier. Conventional portable amplifiers have a number of limitations. Amplifiers that are optimized for weight often sacrifice sound quality by being made of materials that are less acoustically ideal, such as plastic. These amplifiers often only have one speaker driver.